The production of lactic acid-based polymers, specifically polylactic acid (PLA) polyesters, via ring opening polymerization of lactide monomer has been of interest for many years. The ring-opening polymerization of lactide has been studied extensively in hopes of producing useful bio-friendly polymeric materials from renewable resources (e.g., those that can be replenished through biomass production) as an alternative to materials that are based solely on non-renewable resources, e.g., petroleum-based materials.
Various approaches have been taken in an attempt to obtain lactide-based polymeric materials having desired product characteristics. For example, copolymerization with other materials and preparation of substituted polylactides have been examined. For instance, Chen, et al. have examined direct copolymerization of lactide with oxirane using a wide range of tin and aluminum based organometallic catalysts (‘Synthesis and Characterization of [L]-Lactide-Ethylene Oxide Multiblock Copolymers’, Macromolecules, 1997, 30 (15), 4295-4301).
Unfortunately, the copolymers obtained from such processes tend to have limited application. This has been due to both problematic processing characteristics as well as product characteristics. For instance, lactide-based polymers obtained to date have exhibited less than desirable mechanical properties, thermal properties, and water resistance than is necessary for many applications.
Fluorocarbons, in contrast, can offer many desirable characteristics to their incorporating materials. For instance, perfluoropolyethers (PFPEs), which are liquid fluoropolymers at room temperature, offer a variety of attractive properties including low surface energy, good oxidative stability, good solvent resistance, and high temperature resistance. PFPE has shown utility in medical applications due to the capability of forming PFPE films exhibiting high gas permeability and low permeability to a variety of bacterial agents. Unfortunately, however, fluorocarbons are also considered to be environmentally unfriendly.
What are needed in the art are polymeric materials that are more environmentally friendly and are also capable of displaying acceptable physical characteristics in many diverse fields of use.